Chlorotoloxy-ethyl phosphates



2,829,151 CHLOROTOLOXY-ETHYL PHOSPHATES Edgar c. Britten and Harold R. Slagh, Midland, Mich., assignors to The Dow Chemical Company, Midland, Micln, a corporation of Delaware No Drawing. Application November 3, 1952 Serial No. 318,511

5 Claims. (Cl. 260-461) This invention is directed to phosphates and relates particularly to the alkali metal and alkaline earth metal salts of mono-Z-(4-chloro-o-toloxy)ethyl phosphoric acid. These compounds are crystalline solids substantiallyinsoluble to moderately soluble in water and substantially insoluble in non-polar organic solvents. The compounds of the present invention have been found to be herbicidally ONa ' a Gil-Q 0 onlonlo 1 ONa In preparing the chlorotoloxyethyl phosphoric dichloride intermediate, one molecular proportion of2-(4- chloro-o-toloxy)ethanol is reacted with at least one molecular proportion of phosphorus oxychloride at a temperature of from about 40 to about 80 C. in this phase of the reaction it is preferred to employ a molecular excess of the phosphorus oxychloride and good results are obtained when using from 2 to 5 molecular proportions of phosphorus oxychloride per molecular proportion of the substituted ethanol reactant. The reaction proceeds with the evolution of hydrogen chloride. On completion of the reaction, hydrogen chloride, dissolved in the reaction mixture, is removed as, for example, by passing a current of air or inert gas through the mixture; Any excess phosphorus oxychloride may then be recovered by distillation to obtain the 2-(4-chloro-o-toloxy)ethyl phosphoric dichloride intermediate product as a residue. This product may be further purified as by recrystallization or distillation under reduced pressure if desired. However, for the preparation of technical or commercial products, the crude 2-(4-chloro-o-toloxy)- ethyl phosphoric dichloride can be used directly in the next stage of synthesis.

In practice, the reaction of the substituted ethanol compound with phosphorus oxychloride is conveniently carried out in an inert solvent such as carbon tetrachloride. In such operations, it is efficacious to maintain the temperature of the reaction mixture at the boiling point of the solvent, vaporized solvent being retur'ned to the reaction mixture by reflux condenser. On completion of the reaction, the solvent is recovered in the distillation step as set forth above for the recovery of excess phosphorus oxychloride.

In the second phase of the preparation the 2-(4-chloroo-toloxy)ethyl phosphoric dichloride intermediate is re- 2,829,151 iPatented Apr. 1, 1958 acted with water to obtain 2-(4-chloro-o-toloxy)ethyl phosphoric acid. At least two molecular proportions of water are employed for each molecular proportion of the phosphoric dichloride intermediate. Moderate excess of water is not undesirable, however, large excesses are to be avoided since they may result in difiiculties in separating the substituted phosphoric acid product. The

reaction of the phosphoric dichloride intermediate with water is carried out at a temperature of from about 40 to 100 C. and it is convenient to maintain the reaction mixture under reflux at a temperature of about 1007 C.

' thcdesired alkali or alkaline earth metal 2-(4-chloro-otoloxy)ethyl phosphate. The latter may be further puritied by conventional methods although for most uses drying of the product suflices. 1 The 2-(4-chloro-o-toloxy) ethanol used in preparing the compounds of the present invention may be obtained by reacting an alkali metal 4-chloro-o-cresolate with an equimolecular proportion of ethylene chlorohydrin or ethylene bromohydrin. a white solid melting at 51 to 53 C. and boiling at 1l5-1l9 C. under 1 millimeter pressure. Said 2-(4- chloro-o-toloxy)ethanol is described and claimed as a new compound in the copending application of Dalton B. McCaskey, Serial No. 262,655, filed December 20, 1951.

The following examples illustrate the invention but are not to be construed as limiting the same.

Example 1 37.2 grams (0.2 mole) of 2-(4-ehloro-o-toloxy)ethanol was dissolved with stirring in 200 milliliters of warm carbon tetrachloride and a few crystals of anhydrous magnesium chloride were added. 122 grams (0.8 mole) ofphosphorus oxychloride was added rapidly to the above solution and the resulting mixture was heated to its boiling temperature and under reflux for a period of 2 hours. The reaction proceeds with the evolution of hydrogen chloride. Upon completion of the heating period, the reaction mixture was cooled and a current of air blown through it to remove dissolved hydrogen chloride. A total of 7.28 grams (0.2 mole) of hydrogen chloride was recovered. Thereafter, the carbon tetrachloride and excess unreacted phosphorus oxychloride were recovered by distillation to obtain as a crystalline residue a 2-(4-chloro-o-toloxy)ethyl phosphoric dichloride'product. This product was dried in a vacuum desiccator and recrystallized twice from carbon tetrachloride. The resulting crystals melted at 92 C.

10 grams (0.033 mole) of the above crystalline product Example 2 93 grams (0.5 mole) of 2-(4-chloro-o-toloxy)ethanol was dissolved in 500 milliliters of warm carbon tetra-v 2-(4-ehloro-o-toloxy)ethanol is chloride and a few crystals of anhydrous magnesium chloride and 76.8 grams (0.5 mole) of phosphorus oxychloride added thereto with stirring. This reaction mixture was gradually. heated to boiling temperature and maintained under reflurt for about 45 minutes. The resulting crude reaction product was cooled and blown with air asin Example 1, with total recovery of 17.53 grams (0.48 mole) of hydrogen chloride. 100 milliliters of water was thereafter added portionwise to the product with stirring. The resulting aqueous mixture was heated to boiling temperature and under reflux for about 30 minutes. An acidic aqueous layer and an oily organic layer were formed. The organic layer, consisting of crude 2-(4-chloro-o toloxy)ethyl phosphoric acid, was separated and washed with water. One-third of this product was reacted. with 16.9grams (0.33 mole) of finely divided calcium carbonate with stirring. Carbon dioxide was evolved and the reaction m'utture was thereafter evaporated to dryness to obtain a calcium 2-(4- chloro-o-toloxy) ethyl phosphate product as a white powder substantially insoluble in water.

Example 3 4 tively. These products were white solids slightly soluble in water.

Areas of greenhouse potting soil were fitted and planted with tampala, radish and lettuce seed. Disodium 2-(4- chloro-o-toloxy)ethyl phosphate was applied to the above fitted and planted area at the rate of 4 pounds per acre. The active phosphate compound was applied in sutficient water to wet thoroughly the surface of the treated soil area. Similar fitted and planted. areas were left untreated to serve as a control. Observation several weeks after the treatment showed no apparent germination or growth of any of the test species in the treated area. In contrast, seed of all species in the untreated area had germinated and made vigorous growth.

We claim:

1. As new chemical compounds, phosphates of the class consisting of alkali metal and alkaline earth metal salts of mono-2'(4-chloro-o-toloxy)ethyl phosphoric acid.

2. Sodium 2-(4-chloro-o-toloxy)ethyl phosphate.

3. Potassium 2-(4-chloro o-toloxy)ethyl phosphate.

4. Calcium 2-(4-chloro-o-to1oxy)ethyl phosphate.

5. Magnesium 2-(4-chloro-o-toloxy)ethyl phosphate.

References Cited in the file of this patent UNITED STATES PATENTS 2,345,690 Solmssen Apr. 4, 1944 2,573,769 Lambrech Nov. 6, 1951 2,708,675 Slagh May 17, 1955 

1. AS NEW CHEMICAL COMPOUNDS, PHOSPHATES OF THE CLASS CONSISTING OF ALKALI METAL AND ALKALINE EARTH METAL SALTS OF MONO-2-(4-CHLORO-O-TOLOXY)ETHYL PHOSPHORIC ACID. 